Single-Metal-Anchored 1D Mesoporous Channels to Enable Accelerated Redox Kinetics for Lithium-Sulfur Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) show promise as separators in lithium-sulfur batteries (LSBs).
• Conventional MOFs often exhibit limited catalytic activity and Li+ transport control.
• The precise role of MOF pore structure in Li+ flux and polysulfide conversion requires further clarification.

Purpose of the Study:

• To develop novel azolate hybrid frameworks (AHF-DPDC) with 1D anionic channels for dual-function regulation in LSBs.
• To investigate the impact of incorporating Fe centers on polysulfide redox kinetics and Li+ flux.
• To elucidate the mechanism of enhanced performance through synergistic polysulfide blocking and catalytic conversion.

Main Methods:

• Synthesis of a series of azolate hybrid frameworks (M-AHF-DPDC, M = Fe, Co, Ni).
• Electrochemical testing of LSBs utilizing the synthesized MOF separators.
• Density Functional Theory (DFT) calculations to analyze Fe site interactions with polysulfides.

Main Results:

• Fe-incorporated MOFs (Fe-AHF-DPDC) demonstrated significantly enhanced polysulfide redox kinetics.
• LSBs with Fe-AHF-DPDC separators achieved a high initial capacity (1400.7 mAh g-1) and stable cycling (>700 cycles at 1 C).
• Uniform Li+ deposition and suppressed polysulfide shuttling were observed, outperforming existing MOF separators.

Conclusions:

• The developed MOFs with 1D anionic channels offer a dual-function mechanism promoting uniform Li+ flux and catalyzing polysulfide conversion.
• Fe incorporation is crucial for enhancing catalytic activity and achieving superior electrochemical performance in LSBs.
• This strategy provides a viable pathway for developing high-energy-density rechargeable lithium-sulfur batteries.